This invention relates to power generation through a wind machine. In particular the invention is directed to regulating the rotation of a wind responsive rotor of a wind machine during its normal operating phase and during startup and during wind overspeed conditions.
Among the many problems associated with power generation from wind is the difficulty encountered by variable wind conditions which results in a mechanical output from the wind rotor also being variable thereby making it difficult to obtain useful conversion of the mechanical energy into an electrical generator.
Many solutions have been suggested to overcome this problem including the provision of a variable pitch wind rotor whereby the pitch of the rotor will vary according to changes in wind speed. Mechanical and electrical arrangements to effect this variability, however are complicated, and thus it is preferable to employ a fixed pitch rotor.
Another manner of overcoming the variability of the wind speed has been suggested in the feeding of the mechanically generated energy from the rotor to the electrical generator through a hydraulic system which has the ability to accumulate energy and to subsequently release it.
These problems were realized and have been sought to be resolved in the systems for instance in U.S. Pat. No. 4,280,061 (Lawson-Tancred) and U.S. Pat. No. 4,274,010 (Lawson-Tancred). In the systems of both of these patents, however, there is still omitted the major need of providing a simple manner for conveying the hydraulic power effectively to the electric generator. Both these patents propose multiple pumps in the hydraulic feed line from the rotor with one or more, but not all, of the pumps being bypassed from the system as the rotor speed changes, without direct consideration of the wind speed. Additionally in U.S. Pat. No. 4,274,010 an accumulator piston cylinder arrangement is provided downstream of the multiple pumps for effectively accumulating and releasing energy. The output from the pumps is at a variable pressure and, therefore, of necessity, complex and multiple additional equipment is provided to ensure that the hydraulic power transmitted to turn the generator can be beneficially utilized. For instance in U.S. Pat. No. 4,280,061, a variable angle swash plate motor is used downstream of the multiple pumps associated with the rotor and receives the variable pressure hydraulic output from the multiple pumps to effect this transition of power. Multiple control systems are used to regulate the operation of the multiple pumps, the piston and cylinder accumulator, and the variable hydraulic motor. Additionally the pump means employed require relatively complex constructions, and by-passing of unneeded pumps necessitates an overall design and expense requirement for such multiple pumps which should be avoided.
Another earlier attempt at trying to resolve these problems is disclosed in U.S. Pat. No. 2,539,862 (Rushing), and this system also employed hydraulic accumulators for storing energy and means for electromagnetically engaging different numbers of different sized pumps.
Inherently these systems only go part of the way to providing a practical, economical and viable means for utilizing the variable wind power on the rotor.
Consideration, has to the Applicant's knowledge not provided effective means for starting a fixed pitch rotor and for controlling the rotor in overspeed wind conditions which can result in destruction of the wind machine, and which is obviously essential to solve and thereby provide an overall efficient wind power generating system under all wind conditions.